Inhalers provide an alternative drug-delivery method that permits patients to aspirate medication rather than swallow a pill, or drink or inject medication. In some cases, such as with medications that directly target the patient's lungs, aspiration enables the medicine to reach the target area more quickly. In addition, aspiration may be less painful than other drug-delivery methods.
Many inhalers rely upon mechanical atomizers or pressurized cartridges to dispense medication. The dose delivery of such mechanisms can be dependent upon the force exerted on the activation mechanism, the pressure of carrier gas, and the inhalation force exerted by the user.
As an alternative, electronic inhalers, such as those that utilize plural drop ejectors to dispense medication, may be used. However, the drop volume produced by a given ejector mechanism may vary significantly from the manufacturing target value. This uncertainty in ejected drop volume may result in uncertainty in medication dosage. Furthermore, drop volume may determine where in the pulmonary system drops are absorbed.